Nate said the entrance poll shows Romney getting 31 percent of the vote among those whose households made under $30,000 per year. But he won 48 percent among households between $30,000 and $50,000 per year, 58 percent among those making between $50,000 and $100,000 and 62 percent among those with six-figure incomes.

Nevada’s electorate tonight was relatively well off. As many voters today made over $100,000 per year as under $50,000, according to the entrance polls.

Earlier on the NYT site, David Jones said those making 100k a year were about 25% of the electorate.

So, do the math:

25% of the caucus goers made 100k or more * 62% for Romney = 15.5% of total vote.

50% of the caucus goers make between 50 and 100k * 58% for Romney = 29% of total vote

25% of the caucus goers make less than 50k. If they split evenly between those making less than 30k and those making between 30 and 50k, we get

12.5% of the caucus goers make less than 30k * 31% for Romney = 4.1% of the total vote

12.5% of the caucus goers makes between 30k and 50k * 48% for Romney = 6% of the total vote.

15.5 + 29+ 10.1= 55.6%

This calculation is not very sensitive to the split between those making more or less than 30k. If those making 30-50k are 60% of the total making less than 50k, for example, then Romney’s total vote share goes up only .2%.